Vibration wave motor

Abstract

A movable member of a vibration wave motor is driven by a twist component of an off-plane travelling vibration wave generated by a vibration member in a resonance vibration mode.

What is claimed is: 
     
       1. A vibration wave motor comprising: a vibration member having first and second electrostrictive elements arranged with a phase difference therebetween;   said electrostrictive elements being arranged in a plurality of parallel lines with adjacent electrostrictive cells of said electrostrictive elements in the parallel lines being polarized in opposite polarities;   voltage supply means for supplying to said electrostrictive elements a periodic voltage at a frequency to generate a flexural vibration in said vibration member; and   a movable member in oblique contact with said vibration member adapted to be driven by the flexural vibration generated in said vibration member.   
     
     
       2. A vibration wave motor according to claim 1 wherein said vibration member and said movable member are of ring shape. 
     
     
       3. A vibration wave motor according to claim 1 wherein said electrostrictive elements comprise a plurality of piezoelectric elements. 
     
     
       4. A vibration wave motor comprising: a vibration member having first and second electrostrictive elements arranged with a phase difference therebetween;   said electrostrictive elements being arranged in a plurality of parallel lines with adjacent electrostrictive cells of said electrostrictive elements in the parallel lines being polarized in opposite polarities;   voltage supply means for supplying a period voltage to said electrostrictive elements at a frequency to generate an in-plane vibration in said vibration member; and   a movable member adapted to be driven by the in-plane vibration generated in said vibration member, wherein said vibration member and said movable member are ring-shaped, said electrostrictive elements are arranged on an upper or lower surface of said ring-shaped vibration member, and said ring-shaped movable member contacts either an inner or outer circumference of said vibration member.   
     
     
       5. A vibration wave motor comprising: a vibration member;   first electrostrictive means arranged on a surface of said vibration member;   second electrostrictive means arranged on the surface on which said first electrostrictive means is arranged, said first and second electrostrictive means being arranged in parallel with each other, and being arranged at positions which are shifted in phase relative to each other; and   apply means for applying periodic signals having different phases with respect to each other to said first and second electrostrictive means, wherein said vibration wave motor outputs a vibration wave generated in said vibration member as a driving force.   
     
     
       6. A vibration wave motor according to claim 5, wherein said vibration member is ring-shaped, and said first and second electrostrictive means are ring-shaped and arranged in parallel with each other on said ring-shaped vibration member so that circles defined by said first and second electrostrictive means have a common center. 
     
     
       7. A vibration wave motor according to claim 5, wherein said first and second electrostrictive means comprise a plurality of piezoelectric elements. 
     
     
       8. A vibration wave motor comprising: a vibration member having first and second electrostrictive elements arranged with a phase difference therebetween;   said electrostrictive elements being arranged in a plurality of parallel lines with adjacent electrostrictive cells of said electrostrictive elements in the parallel lines having opposite polarities; and   voltage supply means for supplying to said electrostrictive elements a periodic voltage at a frequency to generate a travelling vibration wave in said vibration member, wherein said vibration wave motor outputs a vibration wave generated in said vibration member as a driving force.   
     
     
       9. A vibration wave motor according to claim 8, wherein said electrostrictive elements comprise piezoelectric elements. 
     
     
       10. A vibration wave motor comprising: a vibration member;   a plurality of first electrostrictive element portions arranged in a parallel line on said vibration member, said first electrostrictive element portions being divided into a plurality of parts, each of said parts being oppositely polarized relative to each other, and each part in each portion being parallel with each other and being arranged with opposite polarities;   a plurality of second electrostrictive element portions arranged in a parallel line on said vibration member, said second electrostrictive element portions being divided into a plurality of parts, each of said part being oppositely polarized relative to each other, and each part in each portion being parallel with each other being arranged with opposite polarities, said first and second electrostrictive element portions being arranged with a phase difference therebetween; and   applying means for applying periodic signal to said first and second electrostrictive element portions, said vibration wave motor outputting vibration wave generated in said vibration member as a driving force.   
     
     
       11. A vibration wave motor according to claim 10, wherein said electrostrictive elements portions are piezo-electric members.